diff --git a/apps/editor/app/page.tsx b/apps/editor/app/page.tsx
index 80fb1a96..a20826c0 100644
--- a/apps/editor/app/page.tsx
+++ b/apps/editor/app/page.tsx
@@ -1,13 +1,22 @@
 'use client'
 
 import { Editor, ItemsPanel } from '@pascal-app/editor'
-import { Layers, Package, Settings } from 'lucide-react'
+import { Hammer, Layers, Package, Settings } from 'lucide-react'
+import Image from 'next/image'
 import Link from 'next/link'
+import { BuildTab } from '@/components/build-tab'
 import {
   CommunityViewerToolbarLeft,
   CommunityViewerToolbarRight,
 } from '@/components/viewer-toolbar'
 
+// The open-source editor only ships the built-in catalog (no uploaded items),
+// so the Library/Community/Mine source chips and tag filters add nothing —
+// drop them and keep the panel to plain categories.
+function EditorItemsPanel() {
+  return <ItemsPanel showSourceFilter={false} showTagFilters={false} />
+}
+
 const SIDEBAR_TABS = [
   {
     id: 'site',
@@ -15,13 +24,47 @@ const SIDEBAR_TABS = [
     component: () => null,
     mobileDefaultSnap: 0.5,
     mobileIcon: <Layers className="h-5 w-5" />,
+    icon: (
+      <Image
+        alt=""
+        className="h-8 w-8 object-contain"
+        height={32}
+        src="/icons/scene.png"
+        width={32}
+      />
+    ),
+  },
+  {
+    id: 'build',
+    label: 'Build',
+    component: BuildTab,
+    mobileDefaultSnap: 0.5,
+    mobileIcon: <Hammer className="h-5 w-5" />,
+    icon: (
+      <Image
+        alt=""
+        className="h-8 w-8 object-contain"
+        height={32}
+        src="/icons/build.png"
+        width={32}
+      />
+    ),
   },
   {
     id: 'items',
     label: 'Items',
-    component: ItemsPanel,
+    component: EditorItemsPanel,
     mobileDefaultSnap: 0.5,
     mobileIcon: <Package className="h-5 w-5" />,
+    icon: (
+      <Image
+        alt=""
+        className="h-8 w-8 object-contain"
+        height={32}
+        src="/icons/couch.png"
+        width={32}
+      />
+    ),
   },
   {
     id: 'settings',
@@ -29,6 +72,15 @@ const SIDEBAR_TABS = [
     component: () => null,
     mobileDefaultSnap: 0.5,
     mobileIcon: <Settings className="h-5 w-5" />,
+    icon: (
+      <Image
+        alt=""
+        className="h-8 w-8 object-contain"
+        height={32}
+        src="/icons/settings.png"
+        width={32}
+      />
+    ),
   },
 ]
 
diff --git a/apps/editor/components/build-tab.tsx b/apps/editor/components/build-tab.tsx
new file mode 100644
index 00000000..48552e55
--- /dev/null
+++ b/apps/editor/components/build-tab.tsx
@@ -0,0 +1,160 @@
+'use client'
+
+import { MaterialPaintPanel, useEditor } from '@pascal-app/editor'
+import Image from 'next/image'
+import { useCallback, useEffect, useRef } from 'react'
+import {
+  Tooltip,
+  TooltipContent,
+  TooltipProvider,
+  TooltipTrigger,
+} from '@/components/toolbar-tooltip'
+import { cn } from '@/lib/utils'
+
+/**
+ * Raw structure-tool kinds the Build tab can activate. These map 1:1 to the
+ * editor's `StructureTool` ids.
+ */
+type BuildToolKind =
+  | 'wall'
+  | 'fence'
+  | 'slab'
+  | 'ceiling'
+  | 'roof'
+  | 'stair'
+  | 'elevator'
+  | 'door'
+  | 'window'
+  | 'column'
+  | 'spawn'
+
+type BuildType = {
+  /** Selection id — equals `kind` for tool types, `'painting'` for paint mode. */
+  id: string
+  label: string
+  iconSrc: string
+  /** Present for structure-tool types (absent for the paint mode). */
+  kind?: BuildToolKind
+  /** Non-placement special mode. */
+  mode?: 'material-paint'
+}
+
+// Same icons + ordering as the community Build sidebar, minus presets.
+const BUILD_TYPES: BuildType[] = [
+  { id: 'wall', label: 'Wall', iconSrc: '/icons/wall.png', kind: 'wall' },
+  { id: 'fence', label: 'Fence', iconSrc: '/icons/fence.png', kind: 'fence' },
+  { id: 'slab', label: 'Slab', iconSrc: '/icons/floor.png', kind: 'slab' },
+  { id: 'ceiling', label: 'Ceiling', iconSrc: '/icons/ceiling.png', kind: 'ceiling' },
+  { id: 'roof', label: 'Roof', iconSrc: '/icons/roof.png', kind: 'roof' },
+  { id: 'stair', label: 'Stairs', iconSrc: '/icons/stairs.png', kind: 'stair' },
+  { id: 'elevator', label: 'Elevator', iconSrc: '/icons/elevator.png', kind: 'elevator' },
+  { id: 'door', label: 'Door', iconSrc: '/icons/door.png', kind: 'door' },
+  { id: 'window', label: 'Window', iconSrc: '/icons/window.png', kind: 'window' },
+  { id: 'column', label: 'Column', iconSrc: '/icons/column.png', kind: 'column' },
+  { id: 'spawn', label: 'Spawn Point', iconSrc: '/icons/site.png', kind: 'spawn' },
+  { id: 'painting', label: 'Painting', iconSrc: '/icons/paint.png', mode: 'material-paint' },
+]
+
+/**
+ * Activate a raw structure draw/cursor tool. Mirrors the editor's own
+ * structure-tool activation (`setPhase`/`setStructureLayer`/`setMode`/`setTool`).
+ */
+function activateBuildTool(kind: BuildToolKind): void {
+  const ed = useEditor.getState()
+  ed.setPhase('structure')
+  ed.setStructureLayer('elements')
+  ed.setCatalogCategory(null)
+  ed.setToolDefaults(kind, null)
+  ed.setMode('build')
+  ed.setTool(kind)
+}
+
+/** Enter material-paint mode — the Build tab's "Painting" category. */
+function activatePaintMode(): void {
+  const ed = useEditor.getState()
+  ed.setPhase('structure')
+  ed.setStructureLayer('elements')
+  ed.setMode('material-paint')
+}
+
+/**
+ * Build tab for the open-source standalone editor — a preset-less replica of
+ * the community Build sidebar. Clicking a type activates its raw tool, drawn
+ * with the kind's own `def.defaults()`. The "Painting" type swaps in the
+ * material-paint panel.
+ */
+export function BuildTab() {
+  const activeTool = useEditor((s) => s.tool)
+  const mode = useEditor((s) => s.mode)
+
+  const isTypeActive = (type: BuildType) =>
+    type.mode === 'material-paint'
+      ? mode === 'material-paint'
+      : mode === 'build' && activeTool === type.kind
+
+  const handleTypeClick = useCallback((type: BuildType) => {
+    if (type.mode === 'material-paint') {
+      activatePaintMode()
+    } else if (type.kind) {
+      activateBuildTool(type.kind)
+    }
+  }, [])
+
+  // On open, land on the first build tool — parity with the community Build
+  // sidebar, so switching to Build immediately arms a usable tool.
+  const didInitRef = useRef(false)
+  useEffect(() => {
+    if (didInitRef.current) return
+    didInitRef.current = true
+    const firstType = BUILD_TYPES.find((t) => t.kind)
+    if (firstType) handleTypeClick(firstType)
+  }, [handleTypeClick])
+
+  return (
+    <div className="flex h-full flex-col gap-3 p-3">
+      <TooltipProvider delayDuration={0} disableHoverableContent>
+        <div
+          className="grid gap-1.5"
+          style={{ gridTemplateColumns: 'repeat(auto-fill, minmax(56px, 1fr))' }}
+        >
+          {BUILD_TYPES.map((type) => {
+            const active = isTypeActive(type)
+            return (
+              <Tooltip key={type.id}>
+                <TooltipTrigger asChild>
+                  <button
+                    className={cn(
+                      'group relative flex aspect-square items-center justify-center rounded-xl p-1 transition-all duration-200',
+                      active
+                        ? 'bg-primary/10 ring-1 ring-primary/50'
+                        : 'bg-muted/40 opacity-70 grayscale hover:bg-muted hover:opacity-100 hover:grayscale-0',
+                    )}
+                    onClick={() => handleTypeClick(type)}
+                    type="button"
+                  >
+                    <Image
+                      alt={type.label}
+                      className="size-full object-contain transition-transform duration-200 group-hover:scale-110"
+                      height={48}
+                      src={type.iconSrc}
+                      width={48}
+                    />
+                  </button>
+                </TooltipTrigger>
+                <TooltipContent className="pointer-events-none" side="top">
+                  {type.label}
+                </TooltipContent>
+              </Tooltip>
+            )
+          })}
+        </div>
+      </TooltipProvider>
+
+      {mode === 'material-paint' ? (
+        <div className="min-h-0 flex-1 overflow-y-auto">
+          <MaterialPaintPanel />
+        </div>
+      ) : null}
+    </div>
+  )
+}
diff --git a/apps/editor/components/scene-loader.tsx b/apps/editor/components/scene-loader.tsx
index 1d8dd224..a3706740 100644
--- a/apps/editor/components/scene-loader.tsx
+++ b/apps/editor/components/scene-loader.tsx
@@ -9,9 +9,12 @@ import {
   type SceneGraph,
   type SidebarTab,
 } from '@pascal-app/editor'
+import { Hammer, Layers } from 'lucide-react'
+import Image from 'next/image'
 import Link from 'next/link'
 import { useRouter } from 'next/navigation'
 import { useCallback, useEffect, useRef, useState } from 'react'
+import { BuildTab } from './build-tab'
 import { CommunityViewerToolbarLeft, CommunityViewerToolbarRight } from './viewer-toolbar'
 
 export interface SceneMeta {
@@ -32,6 +35,33 @@ const SIDEBAR_TABS: (SidebarTab & { component: React.ComponentType })[] = [
     id: 'site',
     label: 'Scene',
     component: () => null, // Built-in SitePanel handles this
+    mobileDefaultSnap: 0.5,
+    mobileIcon: <Layers className="h-5 w-5" />,
+    icon: (
+      <Image
+        alt=""
+        className="h-8 w-8 object-contain"
+        height={32}
+        src="/icons/scene.png"
+        width={32}
+      />
+    ),
+  },
+  {
+    id: 'build',
+    label: 'Build',
+    component: BuildTab,
+    mobileDefaultSnap: 0.5,
+    mobileIcon: <Hammer className="h-5 w-5" />,
+    icon: (
+      <Image
+        alt=""
+        className="h-8 w-8 object-contain"
+        height={32}
+        src="/icons/build.png"
+        width={32}
+      />
+    ),
   },
 ]
 
diff --git a/apps/editor/public/icons/scene.png b/apps/editor/public/icons/scene.png
new file mode 100644
index 00000000..99036b8c
Binary files /dev/null and b/apps/editor/public/icons/scene.png differ
diff --git a/packages/editor/src/components/ui/sidebar/panels/items-panel/index.tsx b/packages/editor/src/components/ui/sidebar/panels/items-panel/index.tsx
index 73d58092..6f3c61d2 100644
--- a/packages/editor/src/components/ui/sidebar/panels/items-panel/index.tsx
+++ b/packages/editor/src/components/ui/sidebar/panels/items-panel/index.tsx
@@ -20,6 +20,8 @@ export function ItemsPanel({
   leadingTile,
   emptyState,
   functionTree,
+  showSourceFilter = true,
+  showTagFilters = true,
 }: {
   items?: AssetInput[]
   /** Called when the search query changes (community edition uses this for server-side search) */
@@ -41,6 +43,16 @@ export function ItemsPanel({
    * hierarchical tree browse instead of the legacy hardcoded category tabs.
    */
   functionTree?: FunctionTreeNode[]
+  /**
+   * Library/Community/Mine source chips. The open-source editor has no
+   * uploaded items (only the built-in catalog), so it hides these.
+   */
+  showSourceFilter?: boolean
+  /**
+   * Placement/functional tag filter chips under the search row. The
+   * open-source editor hides these to keep the panel to plain categories.
+   */
+  showTagFilters?: boolean
 }) {
   // When the embedder supplies a function taxonomy, the hierarchical browse
   // replaces the legacy `furnishTools` category tabs entirely.
@@ -63,6 +75,8 @@ export function ItemsPanel({
     leadingTile={leadingTile}
     onSearchChange={onSearchChange}
     searchResults={searchResults}
+    showSourceFilter={showSourceFilter}
+    showTagFilters={showTagFilters}
   />
 }
 
@@ -72,12 +86,16 @@ function LegacyItemsPanel({
   searchResults,
   leadingTile,
   emptyState,
+  showSourceFilter = true,
+  showTagFilters = true,
 }: {
   items?: AssetInput[]
   onSearchChange?: (query: string) => void
   searchResults?: AssetInput[] | null
   leadingTile?: React.ReactNode
   emptyState?: React.ReactNode
+  showSourceFilter?: boolean
+  showTagFilters?: boolean
 }) {
   const mode = useEditor((s) => s.mode)
   const catalogCategory = useEditor((s) => s.catalogCategory)
@@ -89,8 +107,11 @@ function LegacyItemsPanel({
   const [activeFunctionalTag, setActiveFunctionalTag] = useState<string | null>(null)
   // Library / Community / Mine. Default to Library so first-time users see
   // the curated catalog rather than every uploaded item; clicking the chip
-  // again clears the filter (`null` = show everything).
-  const [activeSource, setActiveSource] = useState<AssetInput['source'] | null>('library')
+  // again clears the filter (`null` = show everything). With the chips hidden
+  // there is nothing to filter by, so start unfiltered.
+  const [activeSource, setActiveSource] = useState<AssetInput['source'] | null>(
+    showSourceFilter ? 'library' : null,
+  )
   const [search, setSearch] = useState('')
   const isServerSearch = onSearchChange !== undefined
   // True when server search is active but results haven't come back yet
@@ -152,7 +173,7 @@ function LegacyItemsPanel({
   const allTags = Array.from(new Set(categoryItems.flatMap((item) => item.tags ?? [])))
   const placementTags = allTags.filter((t) => PLACEMENT_TAGS.has(t))
   const functionalTags = allTags.filter((t) => !PLACEMENT_TAGS.has(t))
-  const hasFilters = allTags.length > 1
+  const hasFilters = showTagFilters && allTags.length > 1
 
   const placementCount = (tag: string | null) =>
     categoryItems.filter((item) => {
@@ -205,9 +226,13 @@ function LegacyItemsPanel({
       <div className="flex shrink-0 flex-col gap-2 border-border/70 border-b p-2">
         <div className="flex items-center gap-1.5">
           {/* Search and source filter take 50/50 of the row. `min-w-0` on
-              both sides lets each half shrink to fit when the panel narrows. */}
+              both sides lets each half shrink to fit when the panel narrows.
+              With the source chips hidden, search spans the full row. */}
           <input
-            className="w-1/2 min-w-0 shrink-0 rounded-lg bg-muted px-2.5 py-1.5 text-xs placeholder:text-muted-foreground focus:outline-none"
+            className={cn(
+              'min-w-0 shrink-0 rounded-lg bg-muted px-2.5 py-1.5 text-xs placeholder:text-muted-foreground focus:outline-none',
+              showSourceFilter ? 'w-1/2' : 'w-full',
+            )}
             onChange={(e) => {
               setSearch(e.target.value)
               onSearchChange?.(e.target.value)
@@ -216,7 +241,7 @@ function LegacyItemsPanel({
             type="text"
             value={search}
           />
-          {sourceChips.length > 0 && (
+          {showSourceFilter && sourceChips.length > 0 && (
             <div className="flex w-1/2 min-w-0 shrink-0 rounded-lg bg-muted p-0.5">
               {sourceChips.map((chip) => {
                 const isActive = activeSource === chip.id